Polyester films (this term includes co-polyester and polyester blend, alloy, and mixture films) have been heavily utilized over the last several decades in a great variety of applications. Oriented polyester film products have been produced as roll goods in both monolayer and coextruded multilayered formats. Frequently, protective liner films (also referred to as premasks) are applied to one or both outer surfaces of such films for protective purposes. The liner film typically provides only a temporary protective function while the useful polyester film it is attached to is in transit between manufacturing facilities and/or to the customer, or being handled or processed. The liner film is designed to be removed by an in-house converting process or by the customer before or upon converting or installation of the useful polyester film by simply peeling the liner film, in sheet form, away from the useful polyester film, and then discarding or recycling the liner film. The liner film typically does not provide any functionality comparable to that of the useful polyester film. For example, if the useful polyester film is an optical polarizing film, the liner film does not provide any meaningful optical functionality or polarizing functionality.
It is also known to design some multilayered polymer films so that constituent layers or sheets, each with similar functionality, can be peeled apart or delaminated from the remainder of the film. One use for such films is in anti-graffiti applications. In such applications, the film in its original form may be applied to a mirror, window, or other item to be protected. The film is made up of highly transparent polymer materials, so that the appearance of the mirror, window, or other item is minimally affected by the film. If graffiti is applied to the exposed surface of the film, an outermost portion of the film, on which the graffiti resides, can be peeled away in continuous sheet form from the remainder of the film. After removal of the outermost portion, the remaining film stays in place on the item, which now appears clean and graffiti-free again. A portion of the film that was originally interior to the film, immediately beneath the outermost portion, becomes the new outermost layer. If graffiti is again applied, the new graffiti will reside on the exposed surface of the new outermost layer. The new graffiti can be removed by peeling away the new outermost layer in continuous sheet form from the remainder of the film. After removal of the new outermost portion, the remaining film stays in place on the item, which again appears clean and graffiti-free. The original film product can be made with up to 4 constituent sheets that can be sequentially removed in this manner to provide protection against repeated acts of defacement. To facilitate removal of only one sheet at a time, the product is made with kiss-cut tab-like features of differing depths near the edge of the film.